Comparison of Viscous and Hysteresis Dampers in Reducing the Seismic Vulnerability of Resistant Steel Buildings Based on the Division of the Building’s Structure into Inner and Outer Parts Having Dynamic Interaction

In order to avoid the adverse consequences of building design based on the conventional regulations, such as the necessity of evacuation of thousands of heavily-damaged buildings and their demolishment and reconstruction, the design of the structure in such a way to be repairable even after a major earthquake is a desired alternative design method. In this regard, the authors of the paper recently proposed dividing the building’s structure into two parts, inner and outer, with different periods, and using hysteresis dampers with suitable properties between them for energy dissipation. In the present study, the use of viscous dampers between the two parts of the structure for energy dissipation has been studied and the optimal locations and damping coefficient of the dampers have been determined. For this purpose, first, by dividing a 5-storey building into two sections and by using viscous dampers at the roof level, formulating the equations of motion and coding them in MATLAB platform, the appropriate damping coefficient of the viscous dampers was obtained. The results showed that by choosing the proper damping values, the system could absorb high amount of energy and significantly reduce the drift of the building stories. Then, three 5-, 8- and 11-story steel braced-frames buildings were designed using ETABS software and were divided into inner and outer parts, and modeled for seismic response analyses in PERFORM-3D software. Based on these analyses, performances of viscous dampers with appropriate damping coefficient and hysteresis dampers with appropriate stiffness and strength were compared. Results show that when viscous dampers with appropriate damping coefficient are used, the maximum story drift will be reduced by approximately 35% in the outer structure and approximately 50% in the inner structure relative to the integrated original structure. However, if the hysteresis dampers are used with the proper stiffness and strength, the maximum story drift relative to the integrated original structure will be reduced by approximately 20% in the outer structure and 65% in the inner structure.